1. Field of the Invention
The present invention relates to an apparatus for packaging mattresses which includes a furling drum in which the mattresses are formed into rolls and which has a plurality of circumferentially by arranged rotatable rollers arranged downstream of a nozzle-type feeding area and defining a forming chambers, and a forming tube in which the rolled mattresses are placed into a sack, a bag or any other wrapping.
2. Description of the Prior Art
For transportation purposes, mattresses are formed into rolls and wrapped using, to this effect, different known devices and procedures.
These procedures and devices take into account, as a rule, the type of mattress to be treated, e.g. thin cushions, full-foam mattresses or campbeds.
Thin cushions are made of soft foam stuffed in a fabric case. Generally, the soft foam is sewn in or the fabric case is equipped with a mounting zip. The foam has a maximum thickness of 8 cm. Devices used for the treatment of thin cushions, generally used as campbeds, are unsuited for the processing of mattresses having a thickness of 10 cm and above. Devices used for the processing of thin cushions include a feeder belt receiving the cushion to be processes and conveying it towards the inlet of a sheet-metal drum where it is furled. The cushion, in order to enable nonskid conveyance, is passed through two contrarotating rollers which, similar to the rollers of a calendar, force the cushion into a subsequent sheet-metal channel the special shape of which compels the cushion to get wrapped round on itself. Not much of a compression is applied onto the cushion during the furling phase, because the design of the system does not enable the transmission of elevated forces and because the cushion is supposed to glide along the metal-sheet wall of the drum. Upon completion of the furling process, when the cushion is completely wrapped round on itself, it is expelled from the drum in the axial direction by a slider. The drum opens into a socket with a tubular film with hot-seal cross beam being slipped over it in such a way as to enable the cushion, upon discharge from the socket, to be introduced into the film bag. The disadvantage of this procedure consists in that no significant reduction of volume can be achieved, due to the design of the system that does not enable a strong compression to be applied during the furling process. This type of machine merely enables the bulky cushion to be rolled up into a compact roll which, once placed in its wrapping, will be easy to handle.
There are also devices that are suited for the packaging of full-foam mattresses made of soft-foam pads stuffed in a plain fabric case or in a case composed of two quilt-fabric plates connected one with another by means of a so-called border or mattress bottom. This type of mattress usually has joining seams all along the circumference of the quilt-fabric plates protected by a welting attachment. The minimum thickness is 10 cm, up to as much as 16 cm in quality products. Foam densities are in the range of up to 35 kg/m.sup.3, at a compression hardness up to 50 (processing method from 1.3 to 1.5).
This type of mattresses can be treated by vacuum packaging. At first, the mattress is fed in its full size into a film packaging machine where it is hermetically sealed in a plastic film. After this, it is placed under a flattening press the compression board of which is connected by a hose to a vacuum pump. The packaging film is cut open precisely where the opening of the vacuum hose rests against the plastic film sheathing, to enable the creation of a vacuum. Pressure is now applied to the press which, as a vacuum is created, compresses the mattress down to a thickness between 1 and 3 cm, at a cycle length of some minutes.
When the desired compression is attained, an operating person activates a signal to release pressure. As the compression board returns to its upper home position, the slot previously applied to the plastic film sheath with a view to enabling the air to be sucked off is quickly sealed again by means of an adhesive tape while the mattress, under the effect of atmospheric pressure, remains in its compressed state. After this, the flat mattress is rolled up and placed in a tubular film bag. In the course of time, while the system is frequently not one hundred per cent hermetical, the mattress will continuously expand until it occupies all the space available inside the tubular film bag. The plastic film bag is sealed by means of adhesive tape, wire or by hot-sealing means. The considerable disadvantages of these procedures and devices consist in that they are highly labour-intensive and time-consuming. The film consumption for a 2-meter mattress is 5 meters plus the tubular film bag. After stuffing the material into the fabric case in the filling machine, a second work cycle is required in the film packaging machine to subsequently hot-seal the mattress in a plastic film wrapping.
Furthermore, the known state of the art includes different types of mattress furling machines. Most of these are based upon on the principle adopted for the box-spring mattress furl-packaging machines. These devices have a centre mandrel and one or more pressure rollers. The mattress, together with one end of a long strip of film, are fed into the machine passing them through the gap defined by the mandrel and the pressure roller. In some embodiments, the film is coiled onto the mandrel before introducing the mattress in order to avoid the latter to get into direct contact with the mandrel. The mattress is flattened by the pressure applied by both the pressure rollers and the mandrel as the mattress and the plastic film are coiled in several layers close around the mandrel. In this process, the mandrel pulls the bottom side while it rotates, with the upper side being squeezed and flattened in one direction. As a result thereof, the joining fabric between the two quilted plates forming the upper and the bottom sides of the mattress is subjected to considerable strain. When the mattress is completely drawn in, strips of adhesive tape are applied at several points onto the plastic film which are rolled up with the mattress as coiling continues. After this, the plastic film is cut off and coiling continues over a given length of adhesive tape, without any plastic film, before the strips of adhesive tape are cut off as well. This produces an extremely tight coil, composed of the mattress and the plastic film, furled in several turns around the mandrel and wrapped on the outside with adhesive tape. Upon completion of the coiling process, the mandrel is withdrawn from the centre of the coil, either by retracting it into a stripping wall or by means of a stripper designed to push the mattress roll laterally off the mandrel. Once stripped off the mandrel, the mattress will undergo an expansion in the direction of its centre. All there remains to do, is to seal the mattress roll on both sides by means of adhesive tape or a cord or by hot-sealing.
The great disadvantage of these devices are to be seen in an extremely elevated film consumption of up to 7 meters per mattress. In addition, the mattress undergoes an extreme compressive strain due to the confined space conditions prevailing inside the compression compartment of a given outer perimeter and with the thick mandrel in its centre. It is due to the afore-mentioned specific properties of the device that lots of packaging material are wasted or that the mattress may be damaged while withdrawing the centre mandrel or soiled by the hydraulic oil necessary to keep the moving parts of the mandrel operative. Sealing the mattress roll with adhesive tape, if automatable at all, is a highly delicate pocedure known to give rise to frequent system failures or breakdowns. It is not possible, as a matter of fact, to conceive a sort of workflow that could be integrated into the work cycle of a semiautomated processing line, due to the fact that each mattress needs to be fed into the gap defined by the pressure rollers and the centre mandrel. The handling time being two to five minutes per mattress, this system offers a very poor productivity.
Other mattress-furling machines have been disclosed which do not use a centre mandrel. Instead, these devices include a superstructure composed of driven rollers defining two semicircles. The rollers are supported in a fulcrum at each end of the semicircle, whereas the free end of each semicircle can be moved in a sort of pincers movement by a power drive, most often pneumatic lock cylinders, to form either a closed or an open drum. The mattress, together with one end of a long piece of plastic film, are introduced in between the end rollers of the open semidrum. The mattress and the plastic film, are flattened, under the pressure exerted by the lock cylinder, between the end rollers and, upon activation of the drive, thrust into the roller drum, where they are guided by the driven roller drums and rolled up. When the mattress is completely drawn in, strips of adhesive tape are applied onto it which are rolled up with the mattress as coiling continues. After this, the plastic film is cut off and coiling continues over a given length of adhesive tape, without any plastic film, before the strips of adhesive tape are cut off as well.
Another variant consists in that a glue is sprayed onto the cutting edge of the plastic-film excess length, said cutting edge being defined by a line parallel to the drum axis, with said cutting edge being sealed by the glue as coiling continues.
Depending on the machine design, the mattress furled into a roll may be simply dropped or removed by hand as the half-shell opens under the action of the lock cylinder. After this, the mattress roll will be be sealed on both sides by means of adhesive tape or by hot-sealing.
There are quite some disadvantages to this procedure as well. Plastic-film consumption is relatively high. The mattress undergoes a more or less intensive torsion affecting the area between the upper and lower plate of the quilted fabric case. While the mattress is prevented from expanding again after the furling process, this will inevitably result in the formation of creasing of the woven drill. Again, sealing with adhesive tape is a rather delicate procedure that would frequently lead to failure or breakdown and that can hardly be automated, unless glue were sprayed onto the plastic-film cutting edge. Furthermore, there is no possibility to have the workflow hereinbefore referred to integrated into the work cycle of a semiautomated processing line, due to the fact that each mattress needs to be fed into the gap defined by the end rollers of the drum half-shells.
It is therefore an object of the present invention to provide an improved device of the above-mentioned type, with a view to having the volume of the mattress reduced by compression for the ease of transport, as well as to arriving at an automated furling process and at the